Conventionally, phosphor-integrated nanoparticle labeling agents are known (for example, Patent Document 1). These phosphor-integrated nanoparticle labeling agents comprise: a probe biological substance capable of binding to a biomolecule to be detected; and a phosphor-integrated nanoparticle.
In Patent Document 1, it is disclosed that, when a first binding group (for example, biotin in Examples (the same applies hereinafter)) is linked to the probe biological substance (primary antibody=anti-HER2 antibody) capable of binding to the biomolecule to be detected (HER2) and a second binding group (streptavidin) capable of binding to the first binding group is linked to the phosphor-integrated nanoparticle, a spacer having an appropriate chain length may be allowed to exist between the first binding group and the probe biological substance as well as between the second binding group and the phosphor-integrated nanoparticle. As a specific example of a linker used for the preparation of the spacer that links the second binding group with the phosphor-integrated nanoparticle, SM(PEG)12 is used in Examples of Patent Document 1. Further, in Patent Document 1, it is also disclosed that, not only an embodiment in which the primary antibody is bound to the phosphor-integrated nanoparticle via a biotin-streptavidin bond as shown in Examples, but also an embodiment in which a secondary antibody is bound to the primary antibody and then the phosphor-integrated nanoparticle is allowed to bind to the secondary antibody via a biotin-streptavidin bond can be adopted.